The 'Vaccine' for Rabies was first developed by Louis Pasteur using:
A. Killed rabies virus
B. Live attenuated rabies virus
C. Weakened virus obtained from the spinal cord of infected rabbits
D. A subunit of the rabies virus
Answer: Option C
Solution (By JKSSB Mock Tests)
In 1885, Louis Pasteur developed the first effective vaccine against rabies. He achieved this by serially passaging the rabies virus (obtained from the saliva of infected dogs) through the spinal cords of rabbits. This process attenuated (weakened) the virus for rabbits but made it virulent for dogs. He then dried the infected spinal cords to further weaken the virus and used this attenuated material to successfully inoculate and protect a boy, Joseph Meister, who had been bitten by a rabid dog.
Explanation:
Crossing over occurs during prophase I of meiosis, not in mitosis. Mitosis produces identical diploid cells, meiosis reduces chromosome number by half, and cytokinesis divides the cytoplasm.
Explanation:
Gibberellins stimulate seed germination by activating synthesis of hydrolytic enzymes (amylase) that break down stored food reserves. They also promote stem elongation. Abscisic acid inhibits germination and promotes dormancy. Ethylene is for ripening, cytokinins for cell division. The GA:ABA ratio determines germination vs dormancy.
Explanation:
The conversion of milk to curd (yogurt) is a fermentation process primarily caused by lactic acid bacteria (LAB), such as Lactobacillus. These bacteria ferment the lactose (milk sugar) into lactic acid. The lactic acid lowers the pH, causing the milk protein (casein) to coagulate and solidify, forming curd. It also improves the nutritional value by producing Vitamin B12.
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